differences between the races."[103]

I may be permitted a remark as to Darwin's attitude towards Lamarck.
While, at an earlier stage, when he was engaged in the preliminary
labours for his immortal work, _The Origin of Species_, Darwin
expresses himself very forcibly against the views of Lamarck, speaking
of Lamarckian "nonsense,"[104] and of Lamarck's "absurd, though clever
work"[105] and expressly declaring, "I attribute very little to the
direct action of climate, etc."[106] yet in later life he became more
and more convinced of the influence of external conditions. In 1876,
that is, two years after the appearance of the second edition of _The
Descent of Man_, he writes with his usual candid honesty: "In my
opinion the greatest error which I have committed, has been not
allowing sufficient weight to the direct action of the environment,
i.e. food, climate, etc. independently of a natural selection."[107]
It is certain from this change of opinion that, if he had been able to
make up his mind to issue a third edition of _The Descent of Man_, he
would have ascribed a much greater influence to the effect of
external conditions in explaining the different characters of the
races of man than he did in the second edition. He would also
undoubtedly have attributed less influence to sexual selection as a
factor in the origin of the different bodily characteristics, if
indeed he would not have excluded it altogether.

In Part III of the _Descent_ two additional chapters are devoted to
the discussion of sexual selection in relation to man. These may be
very briefly referred to. Darwin here seeks to show that sexual
selection has been operative on man and his primitive progenitor.
Space fails me to follow out his interesting arguments. I can only
mention that he is inclined to trace back hairlessness, the
development of the beard in man, and the characteristic colour of the
different human races to sexual selection. Since bareness of the skin
could be no advantage, but rather a disadvantage, this character
cannot have been brought about by natural selection. Darwin also
rejected a direct influence of climate as a cause of the origin of the
skin-colour. I have already expressed the opinion, based on the
development of his views as shown in his letters, that in a third
edition Darwin would probably have laid more stress on the influence
of external environment. He himself feels that there are gaps in his
proofs here, and says